Effect of the thermomechanical processing on the mechanical properties of MA956 alloy. I. Microstructural characterization

Abstract

Both the microstructural characteristics and the texture of the ferritic oxide dispersion strengthened MA956 alloy have been studied after different stages of processing. The material was supplied by INCO Alloys International in three conditions: hot isostatically pressed (HIP), hot extruded + 1,330°C/1 h and hot rolled. Two annealing treatments: 1,100°C/100 h and 1,330°C/1 h were performed on the HIP and hot rolled materials to observe the effect of previous microstructure (or the thermomechanical history) on the final microstructure. In the hot-extruded condition, the initial strong <110> fibre texture evolves towards a very strong <111> texture after 1,330°C/1 h treatment, whereas in the hot rolled condition the initial fibre texture with components <110> and <100> results in a <100> after the same thermal treatment. It is pointed out that this difference in the final texture could be due to the differences in the volume fraction of primary grains with <100> and <111> orientations.